Polarization transfer in Rayleigh scattering of hard x-rays

Abstract

The following errors were introduced in the production process:• In the abstract it says that at θ=90°, a degree of polarization of +0.27%±0.12% was measured. This number should be +27%±12%.• On page 5 there are three occurrences of an amplitude A. All of them should be A P instead. AbstractWe report on the first elastic hard x-ray scattering experiment where the linear polarization characteristics of both the incident and the scattered radiation were observed. Rayleigh scattering was investigated in a relativistic regime by using a high-Z target material, namely gold, and a photon energy of 175keV. Although the incident synchrotron radiation was nearly 100% linearly polarized, at a scattering angle of 90 q =  we observed a strong depolarization for the scattered photons with a degree of linear polarization of 0.27% 0.12% +  only. This finding agrees with second-order quantum electrodynamics calculations of Rayleigh scattering, when taking into account a small polarization impurity of the incident photon beam which was determined to be close to 98%. The latter value was obtained independently from the elastic scattering by analyzing photons that were Compton-scattered in the target. Moreover, our results indicate that when relying on state-of-the-art theory, Rayleigh scattering could provide a very accurate method to diagnose polarization impurities in a broad region of hard x-ray energies.

Validating polarization effects in γ-rays elastic scattering by Monte Carlo simulation

“…However, if the polarization of the scattered photon is not measured, this probability function is calculated using equations (9), (11), and (13). Notably, polarization mixing is important for the multiple scattering events, as well as polarization impurity, encountered in practical situations [3,10].…”

“…Testing polarization transfer requires one to measure the polarization of the scattered photons when the incident photon is polarized. Recently, an experiment was conducted using approximately completely linearly polarized (degree of linear polarization is 98.01%) synchrotron radiation [3]. The polarization of the scattered photons was measured at three different angles for photons of energy 0.175 MeV scattered by gold.…”

“…The availability of high-resolution and high-brightness polarized x-ray and γ-ray beams has facilitated investigation of the polarization effects of elastic scattering of photons in the MeV energy range with unprecedented accuracy. Recently, Blumenhangen et al [3] measured the polarization transfer caused by elastic scattering of polarized 0.175 MeV photons scattered off gold atoms. They reported strong depolarization of nearly 100% polarized synchrotron radiation.…”

“…Other theoretical works have focused on polarization effects in Rayleigh scattering beyond nonrelativistic limits [8,9]. More recently, Surzhykov et al [10] proposed the use of Rayleigh scattering as a polarization-diagnostic tool, supported by the experimental results reported in [3]. Nonetheless, these calculations are limited to low energies, where Delbrück scattering has a minimal effect.…”

Polarization reconstruction algorithm for a Compton polarimeter

“…Combining energy, position and time information of each interaction then allows a reconstruction of the Compton scattering events [14]. A series of recent measurements demonstrated the detector ability for precise and efficient linear polarization studies [4,15,16,17]. Depending on the crystal material and thickness, which can reach up to about 2 cm, polarimeters of the aforementioned type can be tailored to incident photon energies ranging from a few dozen keV up to the MeV regime.…”